1. Field of the Invention
The present invention relates to flexible printed circuit boards and, particularly, to a flexible base for making flexible printed circuit boards.
2. Description of Related Art
Flexible printed circuit boards (FPCBs) are widely used in portable electronic devices such as mobile phones, digital cameras and personal digital assists (PDA). In some circumstances, parts within the electronic devices may move relative to the main body. In such situations, FPCB can maintain the electrical connection between the main body and the movable parts due to their excellent flexibility.
Nowadays, roll-to-roll process is employed for mass-producing FPCBs. In order to implement roll-to-roll process, a large sheet of raw material is divided into a number of tape-shaped substrates. Sizes of tape-shaped substrates can be predetermined according to the sizes of the desired FPCBs. FIG. 5 shows a typical tape-shaped substrate 10. The tape-shaped substrate 10 includes a main region 14 for forming FPCB units therein and two conveying regions 11. The main region 14 is disposed along a lengthwise direction of the tape-shaped substrate 10. Two conveying regions 11 is separately arranged at two sides of the main region 14. Each conveying region 11 includes a number of sprocket holes 12 and a continuous copper layer 13 surrounding the sprocket holes 12. The sprocket holes 12 are disposed along the lengthwise direction of the conveying region 11.
In a roll-to-roll process, the sprocket holes 12 are used to mate with rollers to convey the tape-shaped substrate 10. The continuous copper layer 13 is provided to support the sprocket holes 12, so as to avoid deformations of the sprocket holes 12 during the conveying process. After the FPCB units have been molded, the conveying region 11 will be thrown away. However, during an electro-plating process gold/nickel will be plated on the continuous copper layer 13. Thus, these valuable materials (e.g., gold/nickel) will be wasted when the conveying region 11 is thrown away.
Therefore, a new flexible base is desired to overcome the above-described shortcomings.